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Boosting the Performance Of Sunscreen Formulations



Two specialty additives from Lipo Chemicals improve the aesthetic quality of sunscreen formulations and aid solubility of specific sunscreen actives.



By Thomas Russo and John Chase, Lipo Chemicals, Inc.



Published September 28, 2012
Related Searches: formulations retail skin phase
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Boosting the Performance Of Sunscreen Formulations

SPF sunscreen products are a major market category for both skin and sun care protection as well as long-term, anti-aging skin health. Sunscreen actives are the key ingredients available to protect the skin from immediate UVB sunburn damage and UVA long-term accumulative damaging sunlight rays. The effectiveness of SPF sunscreen products is regulated by the FDA in the US as over the counter (OTC) drug products. This is to insure both product safety and uniform drug delivery as related to approved category one sunscreen actives.

Skin protection through the use of sunscreens is of the highest concern to minimize sun exposure. There is a need for some sunlight exposure for the body to naturally produce vitamin D, but excess UVA sunlight exposure is damaging to the skin. Skin cancer is an ever-growing occurrence in the global population especially among those of fair skin and at a higher rate among people living in geographic areas at or near the equator receiving prolonged exposure of sunlight. Skin health is the second key to preventative protection as accumulative sunlight exposure accelerates the aging process. Excessive sunlight causes irreversible damage to the skin by making the skin lose elasticity, producing a leather-like look and damaging skin cells down to the dermis level which results in fine lines and wrinkles.


Comparison of avobenzone (butyl methoxydibenzoylmethane) solubility in control solution and in Liponate OP-26 solvent. No recrystallization of 3% or 5% sunscreen active.
In creating retail sunscreen products with high SPF to protect the skin, there are issues that make these products less aesthetically pleasing to apply. SPF 30 through SPF 50+ sunscreen formulations generally exhibit a heavy, draggy, oily and/or skin whitening effect. This is due to the specific category of sunscreen actives being used to achieve in-vivo retail product test substantiation results. The overall SPF formulation using these combinations of sunscreen active ingredients can be improved through the use of beneficial ingredient additives. The following two specialty additives will improve the aesthetic quality of sunscreen formulations and aid solubility of specific sunscreen actives.

Orgasol Caresse (INCI: Polyamide-5) is a unique powder that was specifically developed to improve the sensorial properties of aqueous based (oil-in-water) formulations. It is a fine elliptical shaped, free-flowing white powder with a narrow particle size distribution. Orgasol Caresse contributes both water and oil solubility properties making it easy to disperse in water-continuous phase formulations.
Orgasol Caresse possesses a combination of high surface porosity and oil/water affinity to reduce oiliness and reduce the rate of absorption into the skin. Orgasol Caresse is a multifunctional skin care ingredient that improves the aesthetics of a sunscreen formulation and provides a very soft powder finish in all oil-in-water emulsions. Orgasol Caresse leaves an invisible protective cushion on the skin, improves the sensory performance by providing an elegant, luxurious, silky texture and delivers a soft focus final appearance of the sunscreen formulation on the skin.

Panel testing was conducted to validate the sensorial performance benefits of Orgasol Caresse in a sunscreen containing formulation. The study parameters are as follows: An SPF 30 sunscreen formulation containing 3% Orgasol Caresse was evaluated in comparison to the control SPF 30 sunscreen formulation containing 3% nylon-12. There were 10 panelists in the study. The panel responses were tabulated and compiled in the spider chart below:
























The panel results show a marked improvement in the sensorial and aesthetic properties of the SPF 30 sunscreen formulation containing Orgasol Caresse. The formulation containing Orgasol Caresse was perceived to exhibit improved rub-in with reduced tackiness, significantly increased smoothness and final powdery feel on the skin.

The formula below demonstrates the use of Orgasol Caresse in a higher SPF 50 (calculated value) formulation for improved sensorial benefits.
Ingredients: %Wt.
Deionized water 50.60
Carbopol Ultrez 10 (Ruger Chemical) (Carbomer) 0.10
Disodium EDTA 0.10
Preservative 1.00
Liponic EG-1 (Lipo Chemicals)(Glycereth-26) 1.50
Phase B  
Orgasol Caresse (Lipo Chemicals)(Polyamide-5) 3.00
Lipomulse Luxe (Lipo Chemicals)(Cetearyl alcohol (and) glyceryl stearate (and) PEG-40 stearate(and) ceteareth-20) 4.50
Neo Heliopan Type AV (Symrise)(Octinoxate) 7.50
Neo Heliopan Type OS (Symrise)(Octisalate) 5.00
Neo Heliopan Type BB (Symrise)(Oxybenzone) 4.00
Neo Heliopan Type 303 (Symrise)(Octocrylene) 10.00
Ganex V220 (Ashland)(VP/eicosene copolymer) 2.50
Panalane L-14E (Lipo (Ineos)(Hydrogenated polyisobutene) 1.00
Vitamin E acetate (Ruger)(Tocopheryl acetate) 0.10
Liponate NEB (Lipo Chemicals)(C12-15 alkyl benzoate) 9.00
Phase C  
Sodium hydroxide (18% sol.) 0.10

Procedure: In main kettle, weigh out the water, add Ultrez 10 and begin heating to 75-80˚C with propeller agitation. Mix for a minimum of 30 minutes or until no gel lumps are visible, then combine the rest of phase A ingredients and maintain heat at 75-80˚C with propeller mixing. In side kettle, combine phase B ingredients and heat to 75-80˚C. Mix until uniform. Slowly add phase B to phase A and mix for 15 minutes until emulsification is complete. Add C to batch as a neutralizing agent and mix well. Begin cooling batch with mixing. Cool to 25˚C with mixing. Specifications: pH 6.56 + 0.2, viscosity LV T-F helipath @ 0.3rpm = 1,275,000 cps + 10%.

Sunscreen solubility can be a major issue in formulating and then properly delivering the OTC SPF sunscreen actives. Delivery of sunscreen actives must be homogeneous and evenly distributed throughout the formulation. This is a requirement of the OTC drug criteria. Problematic sunscreen actives are oxybenzone (benzophenone-3) and avobenzone (butyl methoxydibenzolymethane).
These two powder sunscreen actives are more difficult to properly solubilize, particularly at their upper regulated use levels. Oxybenzone has a maximum use level of 6% as a sunscreen active.

Avobenzone currently has a maximum use level of 3% as a sunscreen active. The concerns are with proper solubility of the powder sunscreens and the prevention of re-crystallization of these actives into needle like crystals. If re-crystallization occurs it is both aesthetically unpleasant and unappealing in a formulation and contrary to the OTC drug criteria for homogeneous delivery of active(s).

Liponate OP-26 (INCI: PPG-26 oleate) is an emollient ester that has beneficial solubility properties for sunscreen actives. It is a medium weight emollient that produces good slip and smooth rub-out on the skin. Liponate OP-26 exhibits a more appropriate skin care feel than the light and dry feeling of C12-15 alkyl benzoate that is traditionally used as a solubilizer.


Comparison of oxybenzone (benzophenone-3) solubility in ‘control’ solution and in Liponate OP-26 solvent. No re-crystallization of 6% sunscreen active.
A solubility study was conducted to evaluate Liponate OP-26 as a solubilizer for 6% oxybenzone, 3% and 5% avobenzone as compared to C12-15 alkyl benzoate. The solutions were prepared by mixing and heating the combinations to 50°C to insure full solubility of each powder sunscreen active. The solutions were cooled to 21°C and allowed to stand sealed for daily and weekly evaluations. The key criteria were that the solutions were homogeneous and that crystallization of the sunscreen actives did not occur. The results of the study show that the 6% oxybenzone in Liponate OP-26 is stable for greater than six months at 21°C with no crystal formation. This is equal in performance to the C12-15 alkyl benzoate control. The avobenzone study shows equal results for the 3% and 5% avobenzone solutions in Liponate OP-26 as compared to the C12-15 alkyl benzoate control after 4 months at 21C. No crystal formation has been observed. Shown below are the solution test samples: Solutions are free of any sunscreen active crystals:

The next step in the study was to evaluate the solubility of Liponate OP-26 in a sunscreen formulation to further confirm both the aesthetic and sunscreen active solubility benefits. The SPF 30 (calculated value) formulations below were prepared and stability tested. The formulations that follow were both stable without sunscreen re-crystallization and were aesthetically more pleasing with Liponate OP-26.

Ingredients: %Wt.
Phase A  
Deionized water 61.70
Preservative qs
Liponic EG-1 (Lipo Chemicals)(Glycereth-26) 1.50
Ultrez 10 (Lubrizol)(Carbomer) 0.20
Phase B  
Lipomulse 165 (Lipo Chemicals)(Glyceryl stearate (and) PEG-100) 4.00
Lipocol SC (Lipo Chemicals)(Cetearyl alcohol) 1.50
Neo Heliopan Type AV (Symrise)(Octinoxate) 7.50
Neo Heliopan Type OS (Symrise)(Octisalate) 5.00
Neo Heliopan Type BB (Symrise)(Oxybenzone) 3.00
Neo Heliopan 303 (Symrise)(Octocrylene) 5.00
Lipopeg 100-S (PEG-100 stearate) (Lipo Chemicals) 0.30
Panalane L-14E (Lipo/Ineos)(Hydrogenated polyisobutene) 1.00
Vitamin E Acetate (Ruger Chemical)(Tocopherol acetate) 0.10
Liponate OP-26 (Lipo Chemicals)(PPG-26 oleate) 9.00
Phase C  
Sodium hydroxide (18% sol.) 0.20

Procedure: Start mixing the water with high speed propeller agitation. Slowly sprinkle in the Ultrez 10 powder until evenly dispersed. Heat the water to 80˚C and add remaining phase A ingredients with continued mixing. In a side kettle, combine Phase B ingredients and heat to 80˚C. Mix until uniform. Slowly add phase B to phase A and mix for 15 minutes until emulsification is complete. Slowly cool batch to 50˚C with mixing and add phase C to batch as a neutralizing agent and mix well. Begin cooling batch further with mixing. Cool batch to 25˚C with mixing. Specifications: pH 6.51, viscosity T-F helipath @ 3rpm = 178,400 cps ± 10%, stability 1 month at 50˚C.

Ingredients: %Wt.
Phase A  
Deionized water 61.40
Preservative qs
Liponic EG-1 (Lipo Chemicals)(Glycereth-26) 1.50
Phase B  
Lipomulse Luxe (Lipo Chemicals)(Cetearyl alcohol (and) glyceryl stearate (and)PEG-40 stearate (and) ceteareth-20) 5.50
Neo Heliopan Type AV (Symrise)(Octinoxate) 7.50
Neo Heliopan Type OS (Symrise)(Octisalate) 5.00
Neo Heliopan Type BB (Symrise)(Oxybenzone) 3.00
Neo Heliopan 303 (Symrise)(Octocrylene) 5.00
Panalane L-14E (Lipo (Ineos)(Hydrogenated polyisobutene) 1.00
Vitamin E Acetate (Ruger Chemicals)(Tocopheryl acetate) 0.10
Liposorb S-20 (Polysorbate 60) (Lipo Chemicals) 1.00
Liponate OP-26 (PPG-26 oleate) (Lipo Chemicals) 9.00
Phase C  
Sodium hydroxide (18% sol.) qs

Procedure: Start mixing the water with medium speed propeller agitation while heating to 80˚C, add the remaining phase A ingredients with continued mixing. In a side kettle, combine phase B ingredients and heat to 80˚C. Mix until uniform. Slowly add phase B to phase A and mix for 15 minutes until emulsification is complete. Cool batch to 25˚C with mixing and, if necessary, adjust pH with phase C. Begin cooling batch further with mixing.

This article highlights the benefits of Orgasol Caresse and Liponate OP-26 (two specialty ingredient additives) that can separately influence SPF Sunscreen formulations by improving the aesthetic qualities, aiding sunscreen solubility and providing greater consumer appeal. As an additional approach, Orgasol Caresse can be combined with Liponate OP-26 in the same formulation to provide an increased two fold benefit. The performance attributes of each ingredient will aid formulation development to insure the highest level of consumer appeal especially for SPF 30 and SPF 50+ sunscreen products.

More info: Lipo Chemicals, www.lipochemicals.com


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